Data over opinions

During London’s 1854 cholera outbreak, many officials blamed “bad air.” Physician John Snow mapped the deaths and found they clustered around one water pump. The map gave him evidence to challenge the prevailing theory.

UX teams make similar mistakes. Stakeholders bring opinions, designers bring hunches, and both can be wrong about what users need.

Opinions and intuition are useful for generating ideas. Research and usage data help us decide whether those ideas work.

In practice, that means:

• Forming hypotheses from intuition and experience
• Collecting qualitative and quantitative evidence
• Checking what the data means before acting on it
• Changing course when evidence contradicts our assumptions

Use your instincts to form hypotheses. Use user data to test them. Don’t use data as a substitute for judgment.